使用 HttpClient 从 Web 读取文件

Question

我正在尝试使用 httpclient 从网络读取文件，但收到此错误。我做错了什么？代码示例将不胜感激。

11-02 17:21:09.845: WARN/ActivityManager(67): Launch timeout has expired, giving up wake lock!
11-02 17:21:10.464: WARN/ActivityManager(67): Activity idle timeout for HistoryRecord{405591c0 com.jeffbreunig/.RetrievingAmazonXMLDataActivity}
11-02 17:21:15.534: DEBUG/dalvikvm(310): GC_EXPLICIT freed 7K, 54% free 2537K/5511K, external 1625K/2137K, paused 64ms
11-02 17:21:18.244: DEBUG/SntpClient(67): request time failed: java.net.SocketException: Address family not supported by protocol
11-02 17:21:20.998: DEBUG/(1879): DID NOT WORK
11-02 17:21:21.344: INFO/ActivityManager(67): Displayed com.jeffbreunig/.RetrievingAmazonXMLDataActivity: +21s38ms

代码：

public class RetrievingAmazonXMLDataActivity extends Activity  {

    private static final String TAG = null;
    TextView txt;


    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);


        txt = (TextView) findViewById(R.id.txt);

        String urlToRead = "http://webdev4.matcmadison.edu/mbtest/mab/AmazonXML/FileList.txt";
        try {
        String fileList = getContent(urlToRead);

        txt.setText(fileList);

        } catch (Exception e) {
            Log.println(Log.DEBUG, TAG, "DUMP FILES DID NOT WORK");
        }



    }



    public String getContent(String url) {

        String responseBody;

        try {
            HttpClient client = new DefaultHttpClient();
            ResponseHandler<String> responseHandler = new BasicResponseHandler();
            HttpGet getMethod = new HttpGet(url);
            responseBody = client.execute(getMethod, responseHandler);
        }
        catch (Exception ex) {
        Log.println(Log.DEBUG, TAG,"DID NOT WORK");
            Toast.makeText(this, "Request failed: " + ex.getMessage(), 6000).show();
            return "Failure to read from server!";
        }

        return responseBody;

    }

    public void onItemSelected(AdapterView<?> parent, View v, int position, long id)
    {
        String s = String.format("You chose [%s]", items[position]);
    }

    public void onNothingSelected(AdapterView<?>parent) {

    }


}

AndroidManifest.xml

 <?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.jeffbreunig"
          android:versionCode="1"
          android:versionName="1.0">
        <uses-sdk android:minSdkVersion="9" />
        <uses-permission android:name="android.permission.INTERNET"/>

        <application android:icon="@drawable/icon" android:label="@string/app_name">
            <activity android:name=".RetrievingAmazonXMLDataActivity"
                      android:label="@string/app_name" >
                <intent-filter>
                    <action android:name="android.intent.action.MAIN" />
                    <category android:name="android.intent.category.LAUNCHER" />
                </intent-filter>
            </activity>

        </application>
    </manifest>

Answer 1

您必须使用某种线程机制来通过 http 获取数据。我建议使用 AsyncTask。

Answer 2

问题很可能是您在 Android 3.0 及更高版本上执行此操作，对吗？
在那里，您被迫使用 AsyncClass 来消费 Web 服务或从互联网下载某些内容，因为您的主 UI 线程不能无响应（长时间运行的代码“锁定”UI 线程的时间是有限制的）;-)